轨道工会砍，怎么拉两个不同的查询起来 [英] rails union hack, how to pull two different queries together

问题描述

我有搜索两个不同的领域，在同一个表...寻找这是最有可能的一个特定城市位置的查询，也可以是一个国家...即需要两个字段。

I have a query which searches two separate fields in the same table... looking for locations which are most likely a specific city, but could also be a country... ie the need for two fields.

表是这样的：

Country    City

Germany    Aachen
USA        Amarillo
USA        Austin

结果：

Keyword   Sideinfo

Aachen    Germany
USA       Country
Austin    USA
Germany   Country

基本上，我不知道是否有一种更简洁的方式来做到这一点，因为我不得不用两个单独的查询，然后将它们添加在一起，对它们进行排序等等（其中正常工作），

Basically I'm wondering if there is a more concise way to do this because I had to use two separate queries then add them together, sort them, etc. (which works fine):

  def self.ajax(search)
    countries = Location.find(:all, :select=> 'country AS keyword,  "Country" AS sideinfo', :joins => :hotels, :conditions => [ 'hotels.email IS NOT NULL AND country LIKE ?', "#{search}%" ], :group => :country )
    cities = Location.find(:all, :select=> 'city AS keyword, country AS sideinfo', :joins => :hotels, :conditions => [ 'hotels.email IS NOT NULL AND city LIKE ?', "#{search}%" ], :group => :city )
    out = cities + countries
    out = out.sort { |a,b| a.keyword <=> b.keyword }
    out.first(8)
  end

我无法找到如何利用工会的任何信息的ActiveRecord ...

I couldn't find any information on how to unions using ActiveRecord...

推荐答案

做一个UNION查询不是本身可能用ActiveRecord。所以有两种解决办法：

Doing an UNION query is not natively possible with ActiveRecord. So there are two solutions :

• 使用的find_by_sql 为你想让它构建查询。我不会建议吧。
• 使用如工会插件以做UNION SQL查询。

• Using find_by_sql to build your query as you want it. I wouldn't advise for it.
• Using a plugin like union to do a UNION sql query.

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